1. Field of the Invention
The present invention relates to a control target recognition system that detects an object on the basis of a reflected wave having a reflection level of a detection threshold or higher among reflected waves transmitted by a transmitter and received by a receiver, and recognizes a control target of a subject vehicle on the basis of a detection result of the object.
The present invention also relates to a vehicle object detection system that detects objects on the basis of a reflected wave having a reflection level of a detection threshold or higher among reflected waves transmitted by a transmitter and received by a receiver, and further detects an object to be a control target of a subject vehicle among the objects.
2. Description of the Related Art
Such art is known from Japanese Patent Application Laid-open No. 6-174847 that when an obstacle detected by a radar device is temporarily out of detection, information on the obstacle is estimated for a predetermined time thereafter on the basis of information on the obstacle that has been stored in a storage device theretofore, and a possibility that a subject vehicle may come into contact with the obstacle is determined on the basis of the estimated information.
Also, Japanese Patent Application Laid-open No. 2008-40646 (Japanese Patent Application No. 2006-211839: filed on Aug. 3, 2006) by the same inventor proposes, in a second embodiment, a system for performing automatic deceleration or warning for avoiding a collision with a stopping object located forward of the subject vehicle such as a low gate through which a subject vehicle can pass or a preceding vehicle, in which when the stopping object is not detected as a target, an extrapolation processing (predicting a future position or the like of the undetected target, and handling the target as if it has been detected) is performed five times thereafter, thereby allowing automatic deceleration or warning for avoiding a collision to be carried out without any trouble even when the target is temporarily undetectable.
Next, with reference to FIGS. 7A to 7J, problems of the system proposed in Japanese Patent Application Laid-open No. 2008-40646 will be described. In FIGS. 7A to 7J, ● denotes actual data and ◯ denotes extrapolated data.
FIG. 7A shows a state of Time 1 where a low gate as a stopping object through which a subject vehicle can pass is located forward of the subject vehicle, and a stopping vehicle as a stopping object is located forward of the gate. In this case, the subject vehicle is unlikely to collide with the gate through which the subject vehicle can pass, and thus collision avoiding control only for the stopping vehicle is desirably performed.
Electromagnetic waves are transmitted forward from a radar device mounted in the subject vehicle, reflection levels of reflected waves from the gate and the stopping vehicle are compared with a detection threshold, and a stopping object having a reflection level of a reflected wave of the detection threshold or higher is a target of the collision avoiding control such as automatic braking or warning. In FIG. 7A, a reflection level of the gate closer to the subject vehicle is the detection threshold or higher, but the distance of the gate is beyond an activation area of the collision avoiding control, and thus the collision avoiding control such as automatic braking or warning is not performed. Also, the stopping vehicle is distant and thus the reflection level of the reflected wave is lower than the detection threshold, and collision avoiding control for the stopping vehicle is naturally not performed.
At Time 4 in FIG. 7B, besides the reflection level of the reflected wave of the gate, the reflection level of the reflected wave of the stopping vehicle becomes the detection threshold or higher, but the distances of the gate and the stopping vehicle are beyond the activation area of the collision avoiding control, and thus the collision avoiding control such as automatic braking or warning for the gate and the stopping vehicle is not performed.
At Time 5 in FIG. 7C, the subject vehicle further approaches the gate, and most of the electromagnetic waves from the radar device pass through the inside of the gate to reduce the reflection level of the reflected wave of the gate, but the reflection level is still the detection threshold or higher, and the state at Time 4 in FIG. 7B is continued.
At Time 6 in FIG. 7D, the subject vehicle further approaches the gate, the reflection level of the reflected wave becomes lower than the detection threshold and the gate is lost sight of (undetectable), and thus a first extrapolation processing for predicting a position of the gate is performed. Also at this time, the distances of the extrapolated gate and the stopping vehicle are beyond the activation area of the collision avoiding control, and thus the collision avoiding control such as automatic braking or warning for the gate and the stopping vehicle is not performed.
At Time 7 in FIG. 7E, the gate is still lost sight of, and thus a second extrapolation processing for predicting the position of the gate is performed. Also at this time, the distances of the extrapolated gate and the stopping vehicle are beyond the activation area of the collision avoiding control, and thus the collision avoiding control such as automatic braking or warning for the gate and the stopping vehicle is not performed.
At Time 8 in FIG. 7F, the gate is still lost sight of, and thus a third extrapolation processing for predicting the position of the gate is performed. In this case, the distance of the extrapolated gate is within the activation area of the collision avoiding control, and thus the collision avoiding control such as automatic braking or warning is performed for avoiding a collision with the gate. However, the gate is the stopping object through which the subject vehicle can pass and does not require the collision avoiding control, and thus unnecessary collision avoiding control is performed.
At this time, the collision avoiding control is not automatic braking but warning, and if a driver ignores the warning and advances the subject vehicle, at Time 11 in FIG. 7G, the stopping vehicle enters the activation area of the collision avoiding control, and thus collision avoiding control such as automatic braking or warning for the stopping vehicle is performed.
At Time 12 in FIG. 7H, the stopping vehicle is still detected within the activation area of the collision avoiding control, and thus the collision avoiding control is continued as it is.
At Time 13 in FIG. 7I, the subject vehicle further approaches the stopping vehicle, and thus the stopping vehicle is laterally beyond a detection area of the radar device and the reflection level becomes lower than the detection threshold, and a first extrapolation processing is performed. Then, the collision avoiding control is continued as it is on the basis of first extrapolated data.
At Time 14 in FIG. 7J, a second extrapolation processing is performed, and the collision avoiding control is continued as it is on the basis of second extrapolated data.
Thus, in the conventional system, the extrapolation processing is uniformly successively performed up to five times while the obstacle is lost sight of. Thus, if the extrapolation processing is successively performed up to five times for the stopping object such as the low gate through which the subject vehicle can pass, excessive collision avoiding control may be performed at Time 8 in FIG. 7F, which may provide discomfort to the driver.
Next, with reference to FIGS. 10A to 20B, problems that may occur when the conventional extrapolation processing is performed will be described. In FIGS. 10A to 20B, “A” shows a conventional example, and “B” shows an embodiment.
In a supposed situation, a subject vehicle runs following a preceding vehicle in a tunnel in which illumination lamps as stopping objects are provided on a ceiling at regular intervals, and when the subject vehicle approaches the preceding vehicle and a relative distance therebetween detected by a radar device provided in the subject vehicle becomes lower than a predetermined value, automatic braking of the subject vehicle or warning to the driver is performed to avoid contact therebetween. The radar device has a detection area (hatched area) with a wider lateral width on a more forward side, and in the detection area, a system activation area R2 for stopping objects of actual data and extrapolated data is set in a section closest to the subject vehicle, and a system activation area R1 for a stopping object of the actual data is set forward of the system activation area R2.
The actual data is data actually detected by the radar device, and the extrapolated data is data of a virtual object inserted by a prediction from past actual data so as to prevent an interruption of system activation when the radar device temporarily loses sight of an object. In the conventional example, the extrapolated data is inserted up to five times, and if the extrapolated data is not transferred to the actual data after five extrapolations, the extrapolated data disappears at the time. Thus, with the extrapolated data, vehicle control such as automatic braking or warning is performed on the basis of the extrapolated data as well as the actual data.
In the example in FIGS. 10A to 20B, if an illumination lamp is located within the hatched detection area of the radar device, the illumination lamp is actual data (see the black hexagon), and if the illumination lamp is beyond and backward of the detection area as the subject vehicle runs, the illumination lamp is extrapolated data (see the white hexagon). If five extrapolations are performed by last time, extrapolation is not performed this time, and data (see the hexagon shown by the broken line) disappears.
The radar device also detects the preceding vehicle, and vehicle control such as automatic braking or warning for the preceding vehicle as a moving object is of course performed. The vehicle control for the moving object is not directly related to the present invention directed to a stopping object, and thus details thereof will be omitted.
FIGS. 10A to 19A correspond to Times 1 to 10 with the lapse of time, and serial numbers 1 to 10 are assigned to the illumination lamps from a side of the subject vehicle to a forward side.
At Time 1 in FIG. 10A, the fourth illumination lamp and thereafter are located within the detection area of the radar device and are actual data (black hexagons), and the second and third illumination lamps are extrapolated data (white hexagons). As is apparent from FIGS. 10A and 20A together, actual data does not exist in the system activation area R1 for the stopping object of the actual data, but the extrapolated data of the third illumination lamp exists in the system activation area R2 for the stopping objects of the actual data and the extrapolated data, and thus unnecessary vehicle control such as automatic braking or warning is performed for the third illumination lamp as a control target.
At Time 2 in FIG. 11A and Time 3 in FIG. 12A, the fourth illumination lamp exists in the system activation area R1 for the stopping object of the actual data, and thus unnecessary vehicle control such as automatic braking or warning is performed for the fourth illumination lamp as a control target.
At Time 4 in FIG. 13A and Time 5 in FIG. 14A, actual data of the fourth illumination lamp exists in the system activation area R1 for the stopping object of the actual data, and the extrapolated data of the third illumination lamp exists in the system activation area R2 for the stopping objects of the actual data and the extrapolated data, and thus unnecessary vehicle control such as automatic braking or warning is performed for the third and fourth illumination lamps as control targets.
At Time 6 in FIG. 15A, the actual data of the fourth illumination lamp exists in the system activation area R1 for the stopping object of the actual data, and thus unnecessary vehicle control such as automatic braking or warning is performed for the fourth illumination lamp as a control target.
At Time 7 in FIG. 16A and Time 8 in FIG. 17A, actual data does not exist in the system activation area R1 for the stopping object of the actual data, and neither actual data nor extrapolated data exists in the system activation area R2 for the stopping objects of the actual data and the extrapolated data, and thus vehicle control is not performed.
At Time 9 in FIG. 18A and Time 10 in FIG. 19A, actual data of the fifth illumination lamp exists in the system activation area R1 for the stopping object of the actual data, and thus unnecessary vehicle control such as automatic braking or warning is performed for the fifth illumination lamp as a control target.
As described above, in the conventional example in which the number of extrapolations is set to five, unnecessary vehicle control is intermittently performed for an illumination lamp with which the subject vehicle is unlikely to come into contact as a control target, which provides discomfort to the driver.
To solve this problem, the number of extrapolations can be reduced from five to, for example, two. However, if the number of extrapolations is reduced for all the control targets, a new problem may occur that necessary vehicle control is not performed when a control target is temporarily lost sight of.